Abstract Background It is well established that the aging process triggers various physiological changes, which may manifest as loss of hydration, the degradation of collagen and elastin fibers, ultimately leading to lines, wrinkles, and skin laxity. To restore the skin's youthful appearance, both non-invasive and minimally invasive procedures have been developed. Objectives We aimed to evaluate the safety and efficacy of non-invasive monopolar vs sequential monopolar-bipolar radiofrequency irradiation from a single tip on skin quality in an aged mouse model. Methods The experiment involved male mice aged 4 and 12 months. The Density® radiofrequency device used for irradiation employs both monopolar (Classic-Tip) and monopolar-bipolar (High-Tip) radiofrequency, operating at a frequency of 6.78 MHz. The device features an automatic impedance matching system that measures impedance in real-time and determines the corresponding compensation value. RF irradiation was performed after applying coupling fluid to the dorsal skin of mice (4 cm²) using an energy density of 63.4 J/cm² per shot under anesthesia. RF was applied on day 0; subsequently, the mice were sacrificed on days 1 and 28 for sample harvesting and histological study. Results The RF irradiated group has shown a significant increase in skin hydration and elasticity. The aging control group showed a 1.7-fold reduction in epidermal thickness compared to the young control group. However, in comparison to the aging control group, after 28 days, the RF irradiation group showed a substantially thicker epidermis, up to 1.5-fold thicker (monopolar group: 15.797±1.093 µm, monopolar-bipolar group: 15.600±0.963 µm). The monopolar group showed a 1.8-fold (p 0.05) increase in collagen density; however, the monopolar-bipolar group showed a 2.4-fold (p 0.05) increase. Notably, the monopolar-bipolar group demonstrated a substantial increase in collagen density compared to the controls. Elastin fiber expression significantly increased in both monopolar and monopolar-bipolar groups compared to the controls. However, the highest expression of elastin fibers was observed in the monopolar-bipolar group. Further, PCR analysis confirmed a significant increase in gene markers such as Blimp1, Fsp1, and Dlk1, suggesting that RF irradiation promotes fibroblast differentiation. Conclusions The sequentially monopolar-bipolar RF irradiation (Density® High-Tip) system significantly increases epidermal thickness, collagen, and elastin fiber production and promotes fibroblast cell differentiation compared to the monopolar radiofrequency alone.
Kumar et al. (Fri,) studied this question.